In a semiconductor device, especially in a semiconductor light-emitting device such as a light emitting diode (hereinafter abbreviated as “LED” when appropriate) and a semiconductor laser, a semiconductor element (this is also referred to as “semiconductor luminous element”) is generally sealed by a transparent member (semiconductor device member) made of resin or the like.
In recent years, the above-mentioned semiconductor light-emitting devices have been put to practical use as information displays used outdoors, such as traffic lights and outdoor displays, automotive headlights, and lighting systems, in place of incandescent lamps and fluorescent lamps, because of their high emission efficiency, viewability, ruggedness and the like. However, it is preferable to use a high-power light emitting device (so-called, a “power device”) for those purposes. As a high-power semiconductor light-emitting device, a semiconductor element (chip) measuring 1 mm per side was disclosed, for example, (Non-Patent Document 1). However, it has been difficult to use a semiconductor light-emitting device generally as power device. Therefore, plurally-provided low-power elements have been used conventionally to circumvent the difficulty.
The reason why semiconductor light-emitting devices are difficult to be used generally as power devices is as follows. Namely, in order to increase light output of an LED, for example, the electric power to be supplied should be increased first. However, heat generation also comes to be increased, with increase in electric power supplied. If the LED chip is upsized, for the purpose of preventing increase in heat density, there will be unevenness in thermal expansion coefficients of the sealant and the chip, leading to low adhesion, as peeling of the sealant from the chip.
Epoxy resin, for example, has been used conventionally as the aforementioned semiconductor device member. In addition, a sealing resin that contains a pigment such as a phosphor so as to convert the luminous wavelength of the light emitted from the semiconductor element has also been known.
However, due to high hygroscopicity of epoxy resin, there have been problems of cracks caused by heat from the semiconductor element when the semiconductor device is used for a long time and degradation of the phosphor or the luminous element caused by moisture infiltration.
Also in recent years, with shortening of the luminous wavelength, there has been a problem of dramatic decrease in brightness of the semiconductor device because the epoxy resin degrades and colors when the device is used illuminated for a long time at a high output level.
In view of these problems, silicone resin, which is superior in heat resistance and ultraviolet-ray resistance, has been used as a substitute for epoxy resin. However, silicone resin does not yet have sufficient adhesion, transparency and weather resistance. Meanwhile, inorganic sealants, which are materials excelling in heat resistance and ultraviolet-ray resistance, and semiconductor devices using such sealants have been proposed (Refer, for example, to Patent Documents 1 to 6).
Non-Patent Document 1: Yukio Narikawa et al., “Oyo Butsuri”, Vol. 74, 11th issue, p. 1423 to p. 1432, 2005
Patent Document 1: Japanese Patent Publication No. 3275308
Patent Document 2: Japanese Patent Laid-Open Publication No. 2003-197976
Patent Document 3: Japanese Patent Laid-Open Publication No. 2004-231947
Patent Document 4: Japanese Patent Laid-Open Publication No. 2002-33517
Patent Document 5: Japanese Patent Laid-Open Publication No. 2002-203989
Patent Document 6: Description of Japanese Patent Application No. 2006-047274